Ecology

1
Ecology

• Symbioses, Biomes, Succession and Biodiversity

2
Definitions

• Ecology- the interaction of organisms and their
  environment
• Biotic factors- living factors in an environment
• Abiotic factors- non-living factors in an
  environment
• Autotroph- producers
• Heterotroph- consumers
• Habitat- where an organism lives
• Niche- what an organism does

3
Levels of Organization

• Biosphere
• Biome
• Ecosystem
• Community
• Population
• Organism
• Organ System
• Organ
• Tissue
• Cell
• Molecule
• Atom

4
Food Chain
5
Food Chains

• Show flow of energy and matter
• Energy decreases along food chain
• Matter is conserved along food chain
• Decomposers break down large molecules into small
  ones that can be used by living things.
• There is a limit to the number of trophic levels
  in a food chain

6
Food Web
7
Ecological Pyramids

• Pyramid of Numbers- exception when producer is
  extremely large in comparison to consumer
• Pyramid of Biomass- exception when producer has
  an exceptionally fast reproductive rate in
  comparison to the consumer
• Pyramid of Energy no exceptions

8
Species Interactions- Symbioses

• Mutualism when both species benefit (oxpecker
  birds and giraffe) (each partner is a symbiont)
• Commensalism- when one species benefits and the
  other is not affected (barnacle whale)
• Predation/Parasitism- one species benefits, the
  other is harmed (lion zebra tick dog)
• Predator eats Prey predators usually larger
  than prey
• Parasites eat from Host parasites usually
  smaller than host

9
Mutualism

Oxpecker birds and water buffalo
10
Mutualism

• Tick bird and antelope

11
Mutualism
Cleaner fish and eel

• Cleaner fish and wrasse

12
Mutualism

• A remarkable 3-way mutualism appears to have
  evolved between an ant, a butterfly caterpillar,
  and an acacia in the American southwest. The
  caterpillars have nectar organs which the ants
  drink from, and the acacia tolerates the feeding
  caterpillars. The ants appear to provide some
  protection for both plant and caterpillar.
• See next slide

13

14
Mutualism

• Perhaps the best documented case of symbiosis is
  the one involving the anemonefishes of the genus
  Amphiprion (Pomacentridae) that dwell among the
  tentacles of tropical sea anemones. The latter
  animals are capable of stinging most fishes, but
  the anemonefishes possess a special mucous
  coating that somehow prevents the discharge of
  the anemone's stinging cells. Both partners
  apparently benefit from the relationship. The
  fish is protected from predators by the stinging
  cells and the anemone, in turn, is guarded
  against anemone-eating fishes by its highly
  territorial fish occupants.

15

• Anemone fish

Sea Anemone
16
Predation
17
Predation
Leopard and prey
Lion and prey
18
Predation

• Chameleon uses tongue to get grasshopper

19
Predation
Mantis eating moth
Crabs eating baby turtle
20
Predation

• Snake eats a rat

21
Parasites
22

• Competitive Exclusion Principle
• When two species compete, the more fit species
  will win out and persist and the less fit species
  will lose or become extinct.
• Therefore
• Two species that have exactly the same
  requirements cannot coexist in exactly the same
  niche.

23

• Exponential Growth Curve

24
Growth Curves-2

• Logistic Growth Curve
• 1.Acclimation stage
• 2.Exponential growth
• 3.Growth slows down
• 4.Population stabilizes (at carrying capacity)

25
What are growth curves used for?

• Predicting population sizes
• Managing populations
• Wildlife management

26
Limiting Factors

• Any biotic or abiotic factor that restricts the
  existence, numbers, reproduction or distribution
  of organisms.
• Density dependent factors- usually operate only
  when a population is large and crowded.
  (competition, predation, parasitism, and
  crowding)
• Density independent factors- factors which affect
  population size regardless of how large the
  population is. These are usually weather related
  floods, earthquakes, cold weather etc.

27
Ranges of Tolerance

• Tolerance- the ability to withstand fluctuations
  in biotic an abiotic environmental factors.
• Some species are more sensitive to environmental
  changes than others.
• Examples
• Insects that live in streams can be very
  sensitive to conditions and therefore, they act
  as indicator species- such as the mayfly
• Fish can live only within certain pH ranges may
  require a minimum amount of dissolved oxygen in
  the water

28
Major Land Biomes of the World

• Tundra
• Taiga
• Temperate forest
• Tropical rain forest
• Grassland
• Desert

29
Major biomes are determined mainly by temperature
and rainfall
30
Global distribution of the major land biomes
31
Biomes

• Knowledge of characteristics of biomes is
  important for
• Planning and dealing with environmental issues
• Determining beneficial introductions of new
  species
• Forecast and understand environmental effects of
  human activities.

32
Biomes

• Similar environments lead to evolution of
  organisms similar in form and function but not
  necessarily in genetic heritage. (Convergent
  evolution!)
• Example deserts occur on all continents.
  Although the desert plants look similar, they
  have different heritages.

33
Succession

• Succession- orderly, natural changes that take
  place in communities of ecosystems
• Primary succession- starts on bare rock or lava
• Secondary succession- sequence of changes that
  take place when a community is disrupted by
  natural disasters or human intervention starts
  on soil
• Climax community- a stable, mature community that
  undergoes little or no succession.
• Pioneer species- organisms that colonize an area
  where there are no other living organisms.

34
(No Transcript)
35
Succession in a bog, lake or pond
36
Succession in a pasture
37
Dune Succession
38
Succession on Mount St. Helens after volcano
erupted
39
Biodiversity

• Species are not uniformly distributed over Earth.
• Diversity varies greatly from place to place.
• Healthy and successful ecosystems have a lot of
  biodiversity.

40
Biodiversity

• Factors that increase biodiversity
• Middle stages of succession
• Lower latitudes
• Rich organic soils
• Moderate environmental disturbance
• Physically diverse habitats
• Small variations in environmental conditions
  (temp, ppt, nutrient supplies etc)
• The more diverse habitat allows more niches, and
  more species persist.

41
Biodiversity

• Factors that decrease diversity
• I. Environmental stress
• II. Extreme environments
• III. A severe limitation in supply of an
  essential resource
• IV. Extreme amounts of disturbance
• V. Recent introduction of exotic species
• VI. Geographic isolation

42
Biodiversity

• People affect diversity-- decrease it
• urbanization
• industrialization
• agriculture
• favoring species
• manipulating populations

43
Reasons for Preserving Biological Diversity

• Ethical (they are alive)
• Aesthetic (beauty)
• Economic (benefit humans, directly or indirectly)
• Intellectual (contributions to knowledge)
• Emotive (sense of awe)
• Religious (created by supernatural force/being)
• Recretional (sport, tourism etc.)

44
Review Questions

1. The relationship that exists when two organisms
   live together in such a way that one benefits but
   the other is not affected, is called ____.
2. The relationship that exists when two organisms
   live together and they both benefit, is called
   ___.
3. When one small organism feeds on a larger
   organism, the relationship is called _____
4. The relationship that exists between a water
   buffalo and an oxpecker bird is called ____
5. True/False Biodiversity is high in healthy
   ecosystems.
6. True/False Human behavior increases
   biodiversity.
7. True/False Forest fires can increase
   biodiversity.

45
Review Questions

• 8. T/F- Two organisms can occupy the same
  habitat.
• 9. T/F- The beauty of wildlife is one reason to
  want biodiversity.
• 10. T/F- In general, higher latitudes have
  greater biodiversity.
• 11. T/F- In general, predators are larger than
  their prey.
• 12. T/F- The relationship of the ants,
  caterpillar and acacia plant is known as
  commensalism.
• 13. T/F- Primary succession is when pioneer
  organisms start growing after a forest fire.
• 14. T/F- All ponds, lakes, bogs tend to fill in
  and become dry land rather than bodies of water.